import from CSV into Ruby array, with 1st field as hash key, then lookup a field's value given header row

Question

Maybe somebody can help me.

Starting with a CSV file like so:

Ticker,\"Price\",\"Market Cap\"
ZUMZ,30.00,933.90
XTEX,16.02,811.57
AAC,9.83,80.02
         


        

Answer 1

Like this (it works with other CSVs too, not just the one you specified):

require 'csv'

tickers = {}

CSV.foreach("stocks.csv", :headers => true, :header_converters => :symbol, :converters => :all) do |row|
  tickers[row.fields[0]] = Hash[row.headers[1..-1].zip(row.fields[1..-1])]
end

Result:

{"ZUMZ"=>{:price=>30.0, :market_cap=>933.9}, "XTEX"=>{:price=>16.02, :market_cap=>811.57}, "AAC"=>{:price=>9.83, :market_cap=>80.02}}

You can access elements in this data structure like this:

puts tickers["XTEX"][:price] #=> 16.02

Edit (according to comment): For selecting elements, you can do something like

 tickers.select { |ticker, vals| vals[:price] > 10.0 }